1. Technical Field
The disclosure relates to a polyimide film laminate and a metal clad laminate employing the same, and in particular relates to a polyimide film laminate with high thermal conductivity and voltage breakdown resistance and a metal clad laminate employing the same.
2. Related Art
The trend for manufacturing electronic devices is towards lighter weights, lower volumes, and easier portability. Accordingly, the integration density of electronic devices has drastically increased. Therefore, electronic devices are developed to have high power, high response rates, and small volumes, resulting in devices with highly non-uniform and massive heat flux. Polyimide can be used to serve as an insulation layer of flexible metal foil substrates due to its excellent thermal resistance, electrical properties, and mechanical properties. In order to solve the heat dissipation issue of high-integrated and high-performance electronic devices and increase the reliability and operating life of the electronic devices, an insulation layer with high thermal conductivity, which provides a short thermal path for heat transfer, is required.
U.S. Pub. No. 2006/0127686(A1) discloses a polyimide film including inorganic particles such as aluminum oxide, silicon oxide, boron nitride, boron oxide covered by aluminum nitride, aluminium powder, silicon dioxide, silicon carbide, aluminium nitride, titanium dioxide, calcium phosophide, or barium titanium. The inorganic particle has a weight percentage of 40˜85 wt %, and the polyimide films as disclosed in the embodiments exhibit a thermal conductivity of less than 1.0 about watts/m ·K.
JP 9137060 (A) discloses the use of boron nitride or aluminum nitride to increase thermal conductivity of a polyimide film. The filler has an average particle size of 0.1 to 10 micrometers, and a resulting polyimide film has a thermal conductivity ranging from 0.2 to 0.6 watts/meter·K.
U.S. Pat. No. 5,078,936 teaches the use of carbon black to enhance the conductivity of the polyimide film; however, both the thermal conductivity and electric conductivity are also increased, wherein applications thereof are restricted to applications which require electric conduction.
As disclosed above, although the conventional polyimide film employing inorganic fillers has improved thermal conductivity, the undesired properties (such as dielectric constant, dielectric loss, and hardness) of the polyimide film are also simultaneously increased. Particularly, an increased rigidity of the polyimide film with high-content fillers will limit its practical applications (for example: poor film-forming ability). Further, a polyimide film with high-conductive fillers (such as nanotube, carbon black, carbon fiber, or graphite) exhibits not only high thermal conductivity but also high electric conductivity, thereby losing the electrical insulating properties of polymeric resin.